Recently, nonwoven fabric has been used in a wide variety of applications because of its excellent air permeability and flexibility. Thus, nonwoven fabric is required to have various properties so as to be suitable to its applications and is demanded to have such properties improved.
For example, nonwoven fabrics for paper diapers, sanitary napkins, and other hygienic materials or for base sheets of poultice materials are required to be water resistance and excellent in terms of moisture permeability. Furthermore, some kinds of nonwoven fabrics are required to be extensibility because of their application sites.
To improve the touch and drape of nonwoven fabric, it is effective that the nonwoven fabric is bulky. As a solution to this, many methods have been proposed with approaches in which core-in-sheath or side by side conjugated continuous fiber made of different kinds of polymers is used so that filaments contained in nonwoven fabric are crimpy.
For example, Japanese Unexamined Patent Application Publication No. H10-110372 (Patent Document 1) has proposed a method including the use of a hollow conjugated continuous fiber; this method uses a side by side conjugated continuous fiber that has a hollow and comprises at least two resins having a side by side arrangement and having a melting point difference between the resins of 15° C. or greater.
As another example, National Publication of International Patent Application No. 2002-529617 (Patent Document 2) has proposed a method including the use of a hollow continuous multicomponent fiber comprising different kinds of propylene polymers and other related embodiments.
Then, Examples described in Patent Documents 1 and 2 independently include a method including the use of a hollow conjugated continuous fiber having two components at 50/50.
Furthermore, Patent Document 2 has proposed a hollow conjugated continuous fiber having an eccentric hollow [FIG. 3D in Patent Document 2].
The methods proposed in Patent Documents 1 and 2 give a crimped conjugated continuous fiber; however, continuous-fiber nonwoven fabric that is more excellent in terms of bulkiness may be needed in some applications.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. H10-110372
[Patent Document 2] National Publication of International Patent Application No. 2002-529617